Add `nvm_alias` and unit tests.

nvm.sh

@@ -234,6 +234,24 @@ nvm_binary_available() {
   nvm_version_greater_than_or_equal_to "$1" "$FIRST_VERSION_WITH_BINARY"
 }
 
+nvm_alias() {
+  local ALIAS
+  ALIAS="$1"
+  if [ -z "$ALIAS" ]; then
+    echo >&2 'An alias is required.'
+    return 1
+  fi
+
+  local NVM_ALIAS_PATH
+  NVM_ALIAS_PATH="$NVM_DIR/alias/$ALIAS"
+  if [ ! -e "$NVM_ALIAS_PATH" ]; then
+    echo >&2 'Alias does not exist.'
+    return 2
+  fi
+
+  cat "$NVM_ALIAS_PATH"
+}
+
 nvm_ls_current() {
   local NODE_PATH
   NODE_PATH="$(which node 2> /dev/null)"

test/fast/Unit tests/nvm_alias

@@ -0,0 +1,33 @@
+#!/bin/sh
+
+die () { echo $@ ; cleanup ; exit 1; }
+
+cleanup () {
+  rm -rf ../../../alias/test
+}
+
+. ../../../nvm.sh
+
+OUTPUT="$(nvm_alias 2>&1)"
+EXPECTED_OUTPUT='An alias is required.'
+[ "_$OUTPUT" = "_$EXPECTED_OUTPUT" ] || die "'nvm_alias' produced wrong output; got $OUTPUT"
+
+EXIT_CODE="$(nvm_alias >/dev/null 2>&1 ; echo $?)"
+[ "_$EXIT_CODE" = "_1" ] || die "'nvm_alias' exited with $EXIT_CODE, expected 1"
+
+rm -rf ../../../alias/nonexistent
+
+OUTPUT="$(nvm_alias nonexistent 2>&1)"
+EXPECTED_OUTPUT='Alias does not exist.'
+[ "_$OUTPUT" = "_$EXPECTED_OUTPUT" ] || die "'nvm_alias nonexistent' produced wrong output; got $OUTPUT"
+
+EXIT_CODE="$(nvm_alias nonexistent >/dev/null 2>&1 ; echo $?)"
+[ "_$EXIT_CODE" = "_2" ] || die "'nvm_alias nonexistent' exited with $EXIT_CODE, expected 2"
+
+EXPECTED_OUTPUT="0.10"
+nvm alias test "$EXPECTED_OUTPUT" || die "'nvm alias test $EXPECTED_OUTPUT' failed"
+OUTPUT="$(nvm_alias test)"
+[ "_$OUTPUT" = "_$EXPECTED_OUTPUT" ] || die "'nvm_alias test' produced wrong output; got $OUTPUT"
+
+cleanup
+